Polyvinyl compounds and chlorine containing polymers such as polyvinyl alcohol and polyvinyl chloride have been used in the prior art to impart improved fire retardancy, tensile strength, hydrophilicity, wettability and wickability to polyurethane foams.
Thus for example U.S. Pat. No. 3,846,508 teaches imparting flame retardant properties to a polyurethane foam by incorporation of trichloroethylene/vinyl-acetate copolymer.
In U.S. Pat. No. 3,214,375 an improvement in wicking properties is achieved by mixing polyvinyl alcohol with a wicking material.
U.S. Pat. No. 3,357,939 achieves improved physical properties by admixing polyvinyl chloride with a polyurethane prepolymer.
U.S. Pat. No. 3,046,172 describes sponges of good tensile strength and good elongation properties, said sponges being prepared by incorporation of hollow spheres into a copolymer of vinyl chloride and a vinyl acetate plastisol.
Regarding the effect of water-wetting, polyurethane foam sponges generally show characteristics which fall short of those exhibited by the natural cellulose sponges. In an effort to improve hydrophilicity, U.S. Pat. No. 2,900,278 describes a method of rendering polyurethane foam hydrophilic by impregnation with polyvinyl alcohol which may be insolubilized by treatment with formaldehyde and acid, e.g., sulfuric acid.
This invention relates to reinforced hydrophilic polyurethane foams. More particularly, the invention is concerned with hydrophilic polyurethane foams reinforced with fibers formed from homopolymers and copolymers of polyvinyl alcohol.
Present day foams, especially those used in a wet state such as household sponges, have a tendency to swell considerably when saturated with liquid. Additionally, when returned to the dry state, the foam ofttimes is distorted and in a shrunken condition. Furthermore, the foams, when wetted, are in a weakened condition resulting in tears and rips in the foam even under oridinary usage.
One object of the present invention is to produce a reinforced hydrophilic urethane foam having improved resistance to swelling when wet. Another object of the instant invention is to produce a reinforced hydrophilic urethane foam having improved wet tensile and tear strength. Other objects will become apparent from a reading hereinafter.